feat(web): add play + like to artist detail header

Mirrors the play overlay on ArtistCard from /library/artists: fetches
every track for the artist (server already filters per-user
lidarr_quarantine), shuffles client-side, kicks off playback. Adds a
LikeButton next to it with entityType="artist" so the operator can
favourite an artist from this surface without bouncing back to the
library grid.

Play button is disabled when album_count === 0 or while the fetch is
in flight, so a double-tap can't start two queues.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/routes/artists/[id]/+page.svelte

@@ -1,11 +1,16 @@
 <script lang="ts">
+  import { Play } from 'lucide-svelte';
   import { page } from '$app/state';
   import { createArtistQuery } from '$lib/api/queries';
   import AlbumCard from '$lib/components/AlbumCard.svelte';
+  import LikeButton from '$lib/components/LikeButton.svelte';
   import LibrarySkeleton from '$lib/components/LibrarySkeleton.svelte';
   import ApiErrorBanner from '$lib/components/ApiErrorBanner.svelte';
   import { useDelayed } from '$lib/utils/useDelayed.svelte';
+  import { api } from '$lib/api/client';
+  import { playQueue } from '$lib/player/store.svelte';
   import type { ApiError } from '$lib/api/client';
+  import type { TrackRef } from '$lib/api/types';
 
   const id = $derived(page.params.id ?? '');
   const queryStore = $derived(createArtistQuery(id));
@@ -15,6 +20,32 @@
   const notFound = $derived(
     query.isError && (query.error as unknown as ApiError | undefined)?.code === 'not_found'
   );
+
+  // Mirrors ArtistCard's play overlay: fetch every track for the artist
+  // (server already honours per-user lidarr_quarantine), shuffle client-side,
+  // start the queue. Bypassed when the artist has nothing to play.
+  function shuffle<T>(items: T[]): T[] {
+    const arr = items.slice();
+    for (let i = arr.length - 1; i > 0; i--) {
+      const j = Math.floor(Math.random() * (i + 1));
+      [arr[i], arr[j]] = [arr[j], arr[i]];
+    }
+    return arr;
+  }
+
+  let isStartingPlay = $state(false);
+
+  async function onPlay() {
+    if (isStartingPlay || !id) return;
+    isStartingPlay = true;
+    try {
+      const tracks = await api.get<TrackRef[]>(`/api/artists/${id}/tracks`);
+      if (tracks.length === 0) return;
+      playQueue(shuffle(tracks), 0);
+    } finally {
+      isStartingPlay = false;
+    }
+  }
 </script>
 
 <div class="space-y-4">
@@ -31,11 +62,23 @@
     <LibrarySkeleton variant="grid" count={12} />
   {:else if query.data}
     {@const detail = query.data}
-    <header>
-      <h1 class="text-2xl font-semibold">{detail.name}</h1>
-      <p class="text-sm text-text-secondary">
-        {detail.album_count} {detail.album_count === 1 ? 'album' : 'albums'}
-      </p>
+    <header class="flex items-center gap-4">
+      <div class="min-w-0 flex-1">
+        <h1 class="font-display text-2xl font-medium text-text-primary">{detail.name}</h1>
+        <p class="text-sm text-text-secondary">
+          {detail.album_count} {detail.album_count === 1 ? 'album' : 'albums'}
+        </p>
+      </div>
+      <button
+        type="button"
+        aria-label={`Play ${detail.name}`}
+        onclick={onPlay}
+        disabled={isStartingPlay || detail.album_count === 0}
+        class="flex h-12 w-12 items-center justify-center rounded-full bg-accent text-text-primary shadow transition-transform hover:scale-105 focus-visible:ring-2 focus-visible:ring-accent disabled:opacity-50 disabled:hover:scale-100"
+      >
+        <Play size={24} strokeWidth={1.5} fill="currentColor" class="ml-0.5" />
+      </button>
+      <LikeButton entityType="artist" entityId={detail.id} />
     </header>
 
     {#if detail.albums.length === 0}